Disk cartridge

ABSTRACT

A disk cartridge comprises a cartridge housing ( 12 ) having a disk compartment ( 16 ) formed therein by overlapping a pair of shells ( 13 ), ( 15 ), an optical disk ( 11 ) rotatably stored within the disk compartment ( 16 ) and a pair of shutter members ( 18   a ), ( 18   b ) attached to the cartridge housing ( 12 ) in such a manner that they can be moved and which close and open an opening portion ( 25 ) bored through the cartridge housing ( 12 ) so that a part of the optical disk ( 11 ) can be exposed, wherein the opening portion ( 25 ) is extended in the diametrical direction of the optical disk ( 11 ) through the central portion of the lower shell ( 15 ). Two optical heads can be used simultaneously by widening the opening portion into and from which the turntable, the optical head and the like are inserted and ejected as much as possible, and efficiency with which the optical head approaches the innermost periphery of the disk-like recording medium can be improved.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a disk cartridge having a cartridge housing in which a disk-like recording medium such as an optical disk, a magneto-optical disk and a magnetic disk is stored in a disk compartment so as to become freely rotatable, and particularly to a disk cartridge in which a pair of shutter members are opened and closed to open and close an opening portion by rotating a middle shell which forms a disk compartment between it and an upper shell or a lower shell and part of a disk-like recording medium is exposed from the opening portion when the opening portion is opened.

[0003] 2. Description of the Related Art:

[0004] As a disk cartridge in which a disk-like recording medium in and/or from which audio information, video information or information such as computer data can be recorded and/or reproduced is rotatably stored in a cartridge housing, there is known a disk cartridge having an arrangement shown in FIG. 1, for example. This disk cartridge 1 is a disk cartridge incorporating therein a write once magneto-optical disk 4 in which a user can record and write information such as computer data later on. This disk cartridge has an outward shape shown in FIG. 1.

[0005] As shown in FIG. 1, this disk cartridge 1 includes a cartridge housing 2 comprised of a pair of an upper shell 2 a and a lower shell 2 b, a magneto-optical disk 4 rotatably stored within a disk compartment 3 of this cartridge housing, and the like. The cartridge housing 2 has on its upper and lower surfaces defined an upper and lower opening portion 5 which is extended from the central portion to one side. This opening portion 5 can be opened and closed by a shutter member 6 which can be slid along one side. Reference numeral 6 a designates a presser member which can prevent the tip end portion of the shutter member 6 from being extracted.

[0006] A disk-like metal center hub 7 is provided at the central portion of the magneto-optical disk 4. This center hub 7 is disposed at the position opposing to the inner end portion of the opening portion 5, i.e., at substantially the central portion of the cartridge housing 2. A turntable provided on an information recording and reproducing apparatus body side is mounted on this center hub 7 and the magneto-optical disk is fixed to the center hub by chucking the turntable, whereby the magneto-optical disk 4 is rotated at a predetermined velocity (e.g., constant linear velocity). In this case, an information signal is recorded on or reproduced from the magneto-optical disk 4 by an action of a magneto-optical pickup device whose head portion is inserted into the opening portion 5.

[0007] However, in the related-art disk cartridge 1 having the above arrangement, the shutter member 6 which opens and closes the opening portion 5 has a U-like shaped cross-section. This shutter member 6 is fitted into one side of the cartridge housing 2 and the shutter member 6 is slid along one side of the cartridge housing 2 to thereby open and close the opening portion 5. For this reason, a disk recording and reproducing apparatus side requires a shutter opening and closing mechanism for sliding the shutter member 6 to open and close the opening portion 5, and the related-art shutter opening and closing mechanism is relatively complicated in structure. Further, it is unavoidable that a large space is produced between the cartridge housing 2 and the shutter member 6, and therefore the disk cartridge 1 cannot be prevented from being smudged by very small dusts and the like.

[0008] In recent years, in the stream in which an optical disk is increasing its storage capacity/increasing its recording density, a recording pattern is becoming narrower in pitch and is increasing a linear density. When a recording surface of an optical disk or a magneto-optical disk is smudged by dusts, read or write beam is shielded or when the information recording surface of the optical disk is damaged by scratches, information cannot be read or written normally. For this reason, in the related-art disk cartridge 1, as shown in FIG. 1, the shutter member 6 having substantially the U-like shaped cross-section is attached to one side of the cartridge housing 2 so as to become slidable and is slid along one side of the cartridge housing 2 to thereby open and close the opening portion 5 so that the information recording surface of the optical disk or the like can be protected.

[0009] However, as the optical disk is further increasing a storage capacity/increasing a recording density, very small dusts which are not so influential in the related art becomes more influential in reading and writing of data. Therefore, the shutter member having the above U-like shape cannot prevent the disk cartridge 1 from being smudged by very small dusts. In this case, when the information recording surface of the magneto-optical disk 4 is smudged by very small dusts entered into the cartridge housing 2, the information recording surface of the magneto-optical disk is damaged by dusts so that information cannot be read out from and written in the magneto-optical disk normally.

[0010] In the above disk cartridge 1 according to the related art, the shutter member 6 is located on the disk cartridge 1 at its position in which users can easily touch the shutter member 6. There is then the risk that a user will slide the shutter member 6 to open the opening portion 5 by mistake. In addition, since the shutter member 6 is linearly slid along one side of the cartridge housing 2, there arises a problem that the surface area of the cartridge housing 2 cannot be reduced.

SUMMARY OF THE INVENTION

[0011] In view of the aforesaid aspect, it is an object of the present invention to provide a disk cartridge in which an opening portion in and from which a turntable, an optical head and the like are inserted and ejected is widened as much as possible so that two optical heads can be used simultaneously.

[0012] It is another object of the present invention to provide a disk cartridge in which an optical head can approach the innermost periphery of a disk-like recording medium with high efficiency.

[0013] It is a further object of the present invention to provide a disk cartridge in which a middle shell is made rotatable, a pair of shutter members are opened and closed based on the rotation of this middle shell and end faces of the pair of shutter members are contacted with each other so that the pair of shutter members can be opened and closed smoothly and reliably.

[0014] It is yet a further object of the present invention to provide a disk cartridge in which a space between the pair of shutter members is reduced as much as possible by pressing the pair of shutter members against each other so that a dustproof property and an airtightness of the large opening portion can be improved. 010 According to an aspect of the present invention, there is provided a disk cartridge which is comprised of a cartridge housing in which a disk compartment is formed by overlapping a pair of shells, a disk-like recording medium rotatably stored within the disk compartment and a pair of shutter members rotatably attached to the cartridge housing and exposing part of the disk-like recording medium by opening and closing an opening portion provided on the cartridge housing when they are moved, wherein the opening portion is extended in the diametrical direction of the disk-like recording medium through the central portion of the lower shell or the upper shell.

[0015] According to another aspect of the present invention, in the disk cartridge, the cartridge housing includes a middle shell rotatably supported by the upper shell and the lower shell and the opening portion is formed through the middle shell and the lower shell or the upper shell.

[0016] According to still another aspect of the present invention, in the disk cartridge, the pair of shutter members are comprised of a combination of a pair of substantially semicircular same plate materials, the pair of shutter members are symmetrically disposed on one surface of the middle shell across the opening portion, the guide groove is provided on one side portion of a chord side in each of the shutter members and a shaft portion provided on the other side portion of the chord side is rotatably supported to the middle shell.

[0017] According to a further aspect of the present invention, in the disk cartridge, a pair of guide grooves are provided on one of the pair of shutter members and the cartridge housing, a pair of operation convex portions which are slidably engaged with the guide grooves are provided on the other of the pair of shutter members and the cartridge housing, the guide grooves are moved along the operation convex portions based on the rotation of the middle shell, whereby the pair of shutter members are enabled to open and close the opening portion.

[0018] In accordance with a further aspect of the present invention, there is provided a disk cartridge which is comprised of a cartridge housing in which a disk compartment is formed within an upper shell and a middle shell or the middle shell and a lower shell by overlapping the upper shell, the middle shell and the lower shell and in which the middle shell is rotatably supported by the upper shell and the lower shell, a disk-like recording medium is stored within the disk compartment so as to become freely rotatable, a pair of shutter members are attached to the middle shell in such a manner that they can be moved in the flat surface direction on the same plane and a shutter opening and closing mechanism for tightly closing the opening portion provided on the cartridge housing and from which part of the disk-like recording medium is exposed by moving the pair of shutter members based on the rotation of the middle shell such that end faces of the pair of shutter members are pressed against each other.

[0019] In accordance with yet a further aspect of the present invention, in the disk cartridge, the shutter opening and closing mechanism includes a pair of guide grooves provided on one of the pair of shutter members and the cartridge housing, a pair of operational convex portions provided on the other of the pair of shutter members and the cartridge housing and which are slidably engaged with the guide grooves and the pair of shutter members are enabled to open and close the open and close portion by moving the guide grooves along the operational convex portions based on the rotation of the middle shell.

[0020] In accordance with yet a further aspect of the present invention, in the disk cartridge, the pair of guide grooves include resilient members for imparting spring force to the pair of operational convexs such that the pair of shutter members are spring-biased in the flat surface direction when the pair of shutter members are closed.

[0021] In accordance with still a further aspect of the present invention, in the disk cartridge, the pair of shutter members are comprised of a combination of a pair of substantially semicircular same plate-like materials, the pair of shutter members are symmetrically disposed on one surface side of the middle shell across the opening portion, the guide grooves are provided on one side portions of chord sides of the respective shutter members and pivots provided on the other side portions of the chord sides are supported to the middle shell so as to become freely rotatable. 14 With the above arrangement, in the disk cartridge including the cartridge housing having the disk compartment, the disk-like recording medium and the pair of shutter members, since the opening portion is extended in the diametrical direction of the disk-like recording medium through the central portion of the cartridge housing, two recording and/or reproducing head portions can simultaneously be inserted into the opening portion so that two recording and/or reproducing operations can be executed at the same time. Furthermore, the two recording and/or reproducing head portions can approach the innermost periphery of the disk-like recording medium and therefore, the disk cartridge can approach the innermost periphery of the disk-like recording medium with high efficiency.

[0022] According to the disk cartridge of the present invention, since the cartridge housing includes the middle shell in addition to the upper shell and the lower shell, the middle shell is rotatably supported by the upper shell and the lower shell and the opening portion is provided through the middle shell and the upper shell or the lower shell, there can be formed the opening portion into and from which two recording and/or reproducing head portions can be inserted and ejected simultaneously, and the opening portion can be opened and closed by the pair of shutter members. 16 According to the disk cartridge of the present invention, since the pair of shutter members are comprised of the combination of two substantially semicircular same plate materials, the pair of shutter members are symmetrically disposed across the opening portion, the guide grooves are provided on one side portions of the respective shutter members, the pivots are provided on the other side portions and the pivots are supported to the middle shell so as to become freely rotatable, the opening portion of the wide range can be opened and closed while the areas of the shutter members can be reduced. Therefore, the efficiency with which the opening portion is opened and closed can be increased, and the whole of the disk cartridge can be made compact and thin.

[0023] Further, according to the disk cartridge of the present invention, since the pair of guide grooves are provided on one of the pair of shutter members and the cartridge housing, the pair of operational convexs are provided on the other of the pair of guide grooves and the guide grooves are moved along the operational convexs based on the rotation of the middle shell, the pair of shutter members can be moved with high reliability so that the opening portion can be opened and closed smoothly and reliably.

[0024] Further, according to the disk cartridge of the present invention, in the disk cartridge comprising the cartridge housing having the disk compartment, the disk-like recording medium and the pair of shutter members, since the disk cartridge includes the shutter opening and closing mechanism for moving the pair of shutter members based on the rotation of the middle shell so that the end faces of the pair of shutter members are pressed against each other, the pair of shutter members can be contacted with each other reliably and strongly by rotating the middle shell. Therefore, the disk compartment can be prevented from being smudged by very small dusts and the like by reducing the space between the pair of shutter members and the cartridge housing. Hence, the dustproof property of the cartridge housing can be improved. Moreover, the disk cartridge can be reduced in thickness and improved in space factor so that the whole of the disk cartridge can be made compact and thin.

[0025] Further, according to the disk cartridge of the present invention, since the pair of operational convexs are moved along the pair of guide grooves based on the rotation of the middle shell, the pair of shutter members can be rotated smoothly and reliably.

[0026] Further, according to the disk cartridge of the present invention, since the shutter open and close mechanism presses the pair of shutter members, the two shutter members can be closely contacted with each other so that the dustproof property of the cartridge housing can be improved.

[0027] Furthermore, according to the disk cartridge of the present invention, since the pair of shutter members are comprised of a combination of two substantially semicircular same plate materials and the pair of shutter members are symmetrically disposed across the opening portion, the pair of shutter members can be operated with high reliability. Therefore, the opening portion can be opened and closed smoothly and reliably, and the whole of the disk cartridge can be made compact and thin.

BRIEF DESCRIPTION OF THE DRAWINGS

[0028]FIG. 1 is a perspective view showing a disk cartridge according to the related art;

[0029]FIG. 2 is an exploded perspective view showing a disk cartridge according to a first embodiment of the present invention and illustrates the same disk cartridge from the lower surface side;

[0030]FIG. 3 is a perspective view showing the disk cartridge shown in FIG. 2 from the lower surface side and illustrating the state in which an opening portion is closed by closing a shutter mechanism;

[0031]FIG. 4 is a perspective view showing the disk cartridge shown in FIG. 2 from the lower surface side and illustrates the state in which the opening portion is opened by opening the shutter mechanism.

[0032]FIG. 5 is a plan view showing a lower surface of an upper shell of the disk cartridge shown in FIG. 2;

[0033]FIG. 6 is a plan view showing a lower surface of a middle shell of the disk cartridge shown in FIG. 2;

[0034]FIG. 7 is a plan view showing an upper surface of a lower shell of the disk cartridge shown in FIG. 2;

[0035]FIG. 8 is a perspective view showing the state in which an opening portion is opened by opening a pair of shutter members attached to the middle shell of the disk cartridge shown in FIG. 2;

[0036]FIG. 9 is a perspective view showing the state in which the opening portion is closed by closing the pair of shutter members attached to the middle shell of the disk cartridge shown in FIG. 2;

[0037]FIG. 10 is a perspective view showing the state in which a shutter mechanism is disposed on the lower shell of the disk cartridge shown in FIG. 2 and in which the opening portion is opened by opening the pair of shutter members;

[0038]FIG. 11 is a perspective view showing the state in which the shutter mechanism is disposed on the lower shell of the disk cartridge shown in FIG. 2 and in which the opening portion is closed by closing the pair of shutter members;

[0039]FIG. 12 is a plan view showing the disk cartridge shown in FIG. 11 from the upper direction;

[0040]FIG. 13 is a longitudinal cross-sectional view of the central portion of the disk cartridge shown in FIG. 2 and to which reference will be made in explaining a relationship between the disk cartridge and a turntable;

[0041]FIG. 14 is an explanatory diagram showing a relationship between operations of a cartridge housing and a shutter mechanism of the disk cartridge shown in FIG. 2 and illustrates the state in which the opening portion is completely closed by closing the pair of shutter members;

[0042]FIG. 15 is a plan view showing the outward appearance state of FIG. 14 from the lower shell side;

[0043]FIG. 16 is an explanatory diagram showing the state in which the middle shell is rotated a little from the state shown in FIG. 14 so that the pair of shutter members are opened a little;

[0044]FIG. 17 is an explanatory diagram showing the state in which the middle shell is further rotated a little from the state shown in FIG. 16 so that the pair of shutter members are further opened a little;

[0045]FIG. 18 is an explanatory diagram showing the state in which the middle shell is still further rotated from the state shown in FIG. 17 so that the pair of shutter members are still further opened a little;

[0046]FIG. 19 is an explanatory diagram showing the state in which the middle shell is still further rotated from the state shown in FIG. 18 so that the pair of shutter members are still further opened a little;

[0047]FIG. 20 is an explanatory diagram showing the state in which the middle shell is yet further rotated so that the pair of shutter members are opened completely;

[0048]FIGS. 21A to 21C are diagrams to which reference will be made in explaining the manner in which the middle shell ascends and descends relative to the upper shell when the disk cartridge shown in FIG. 2 is opened and closed, wherein FIG. 21A is an exploded perspective view, FIG. 21B is a perspective view showing the state in which the middle shell descends, and FIG. 21C is a perspective view showing the state in which the middle shell ascends;

[0049]FIGS. 22A and 22B are diagrams to which reference will be made in explaining the manner in which the middle shell ascends and descends when the disk cartridge shown in FIGS. 21A to 21C is opened and closed, wherein FIG. 22A is a cross-sectional view showing the state in which a cam portion of the middle shell is pressed against a lift up portion of the upper shell, and FIG. 22B is a cross-sectional view showing the state in which a cam portion of the middle shell is inserted into a cam groove of the upper shell;

[0050]FIG. 23 is an exploded perspective view showing a disk cartridge according to a second embodiment of the present invention and illustrating the disk cartridge from the lower surface side;

[0051]FIG. 24 is a perspective view showing the disk cartridge shown in FIG. 23 from the lower surface side and illustrates the state in which the opening portion is closed by closing the shutter mechanism;

[0052]FIG. 25 is a block diagram to which reference will be made in explaining a circuit arrangement of a disk recording and reproducing apparatus which uses the disk cartridge according to the present invention;

[0053]FIG. 26 is a perspective view showing the state presented before the disk cartridge shown in FIG. 2 is inserted into the disk recording and reproducing apparatus which uses the disk cartridge according to the present invention; and

[0054]FIG. 27 is a perspective view showing the state in which the disk cartridge shown in FIG. 2 is being inserted into the disk recording and reproducing apparatus which uses the disk cartridge according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0055] A disk cartridge according to embodiments of the present invention will now be described below with reference to the accompanying drawings.

[0056] FIGS. 2 to 27 are diagrams showing disk cartridges according to the embodiments of the present invention. Specifically, FIG. 2 is an exploded perspective view showing a disk cartridge according to a first embodiment of the present invention from a lower shell side. FIG. 3 is a perspective view showing the same disk cartridge with its shutter being closed from the lower shell side. FIG. 4 is a perspective view showing the same disk cartridge with its shutter being opened. FIG. 5 is a bottom view of an upper shell. FIG. 6 is bottom view of a middle shell. FIG. 7 is a plan view of the lower shell. FIG. 8 is a perspective view showing the middle shell and a pair of shutter members being opened. FIG. 9 is a perspective view showing the state in which the pair of shutter members shown in FIG. 8 are being opened. FIG. 10 is a perspective view showing the lower shell and the pair of shutter members being opened. FIG. 11 is a perspective view showing the state in which the pair of shutter members shown in FIG. 10 are being closed. FIG. 12 is a plan view of FIG. 11. FIG. 13 is an explanatory diagram showing the central portion in cross-section.

[0057] FIGS. 14 to 20 are explanatory diagrams showing a relationship between the rotated amount of the middle shell and the opened and closed states of the pair of shutter members, respectively. FIGS. 21A to 21C are explanatory diagrams showing a relationship between the rotation of the middle shell and the ascending and descending operations, respectively. FIGS. 22A and 22B are respectively explanatory diagrams showing the state in which the shutter members are closely contacted/released based on the ascending and descending operations executed when the middle shell is rotated. FIG. 23 is an exploded perspective view showing a disk cartridge according to a second embodiment of the present invention from a lower shell side. FIG. 24 is a perspective view showing the same disk cartridge from the lower shell side. FIG. 25 is a block diagram to which reference will be made in explaining a circuit arrangement of an information disk recording and reproducing apparatus which can use the inventive disk cartridge according to an embodiment of the present invention. FIG. 26 is a perspective view showing the state presented before the disk cartridge according to the present invention is inserted into the disk recording and reproducing apparatus. FIG. 27 is a perspective view showing the state in which the disk cartridge is being inserted into the same disk recording and reproducing apparatus.

[0058] A disk cartridge 10 according to the first embodiment of the present invention stores therein a preformatted optical disk on which various information signals such as a music signal serving as audio information and a video signal and a music signal, both serving as video information, are recorded in advance or an optical disk (write once optical disk) on which an information signal such as audio information and video information can be recorded once or an optical disk (rewritable optical disk) 11 on which an information signal can be recorded many times repeatedly as a disk-like recording medium. However, the disk-like recording medium is not limited to the above optical disks, and a magnetic disk in which information can be memorized by magnetic status of a specific position on a magnetic thin layer formed on the surface of a thin disk, a magneto-optical disk in which information can be written in and read out from the magnetic thin layer formed similarly by using an optical head and a magnetic head and other storage mediums can be applied to the above disk-like recording medium.

[0059] As shown in FIGS. 2 to 4, this disk cartridge 10 comprises a cartridge housing 12 formed by overlapping a pair of an upper shell 13, a middle shell 14 and a lower shell 15, the optical disk 11 stored within a disk compartment 16 formed within this cartridge housing 12 so as to become freely rotatable, a pair of shutter members 18 a, 18 b for opening and closing opening portions 25, 42 provided through the middle shell 14 and the lower shell 15, and the like. In this disk cartridge 10, when the optical disk 11 is in use in the horizontal direction, the upper shell 13 is normally disposed on the upper side. However, for convenience sake of explanation, the upper side and the lower side are reversed in FIG. 2, and hence the upper shell 13 is placed in the lower side.

[0060] The upper shell 13 is a thin disk-like member of substantially a square-shape, the front side of which is shaped as a circular arc as shown in FIGS. 2 and 5. At the central portion of the lower surface (i.e., shown as the surface in FIG. 2) of this upper shell 13, there is provided a circular upper concave portion 19 a into which substantially an upper half of the middle shell 14 in the thickness direction can be fitted so as to become rotatable. When the upper concave portion 19 a is provided on the central portion of the lower surface, a front edge portion 13 a, left and right side edge portions 13 b, 13 c and a rear edge portion 13 d are formed on the outer peripheral edge of the upper shell 13. At substantially the central portions of the front edge portion 13 a and the rear edge portion 13 dof the upper shell 13, there are provided positioning concave portions 21 a and 21 b which are used to properly position the upper shell relative to the lower shell 15. 23 On the outer peripheral edge of the upper concave portion 19 a of the upper shell 13, there are provided three circular-arc-like cam grooves 22, each having a predetermined length, which are continued along the circumferential direction. Then, there are provided the three cam grooves 22, whereby three lift up portions 23 (shown hatched as cross stripes in FIG. 6), each having a predetermined length, between the adjacent cam grooves 22 and 22. A cam portion 46 provided in the middle shell 14 is slidably fitted into the three cam grooves 22.

[0061] The lower shell 15 is overlaped to the lower surface of the upper shell 13. As shown in FIGS. 2 and 7, the lower shell 15 has an outward appearance shape which is substantially similar to that of the upper shell 13 and is formed of a substantially square thin disk-like member whose front side is shaped as a circular arc. On the central portion of the flat surface (surface hidden as the back in FIG. 2) of this lower shell 15, there is provided a circular lower concave portion 19 b into which a substantially lower half portion in the thickness direction of the lower shell 15 is fitted rotatably. When this lower concave portion 19 b is provided on the central portion of the flat surface of the lower shell, a front edge portion 15 a, left and right side edge portions 15 b, 15 c and a rear edge portion 15 d are provided on the outer peripheral edge of the lower shell 15. On substantially a central portion between the front edge portion 15 a and the rear edge portion 15 d of the lower shell 15, there are provided positioning convex portions 24 a and 24 b which are used to properly position the lower shell relative to the upper shell 13.

[0062] The convex portions 24 a, 24 b of the lower shell 15 are respectively engaged with the concave portions 21 a, 21 b of the upper shell 13, whereby the upper and lower shells 13, 15 are properly positioned and overlaped together in a predetermined state. The middle shell 14 is stored within a circular space formed of the upper and lower concave portions 19 a, 19 b formed within the upper and lower shells 13, 15 in such a manner that it may become freely rotatable. An opening portion 25 extended in the front and back direction is provided at the central portion of the lower shell 15. This opening portion 25 is used to allow a turntable of a disk rotary drive mechanism and an optical head of an optical pickup device to face the optical disk 11 and is set to be wide enough so that they can be inserted into and ejected from the opening portion.

[0063] Specifically, the opening portion 25 of the lower shell 15 includes a table opening portion 25 a set at the central portion into and from which the turntable is inserted and ejected and a head opening portion 25 b extended in the front and back direction of the table opening portion 25 a. The shape of this opening portion 25 is devised such that two optical heads can be simultaneously inserted into and ejected from both sides of the table opening portion 25 a in the head opening portion 25 b. On the inner surfaces of both ends of the front and back direction of the head opening portion 25 b, there are respectively provided cover portions 26 a, 26 b which are used to close the spacing between them and shutter members 18 a, 18 b which will be described later on. Further, within the lower concave portion 19 b, there are provided a pair of operational convexs 27 a, 27 b which become symmetrical with respect to the table opening portion 25 a.

[0064] The middle shell 14 is stored within the upper and lower concave portions 19 a, 19 b formed by the upper shell 13 and the lower shell 15 having the above arrangements, and the middle shell 14 and the upper shell 13 constitute a disk compartment 16 formed of a circular spacing portion. Within this disk compartment 16, there is stored the optical disk 11 with a predetermined spacing in the outside of the radius direction and in the thickness direction. This optical disk 11 is formed of a thin disk-like recording member having a center hole 11 a bored at the central portion.

[0065] To one surface of the central portion of this optical disk 11, there is fixed a center hub 28 so as to cover the center hole 11 a by a fixing means such as an adhesive agent. This center hub 28 is formed of a magnetic material such as an iron plate attracted by magnetic force from a magnet (not shown). A turntable of a disk rotary drive apparatus incorporated within a disk recording and reproducing apparatus is fitted through the center hole 11 a to the center hub 28. The center hub 28 is attracted by magnet force from the magnet provided on the turntable. Consequently, the optical disk 11 is chucked to the turntable and integrated in the rotation direction, whereby the optical disk 11 is rotated at a predetermined velocity (e.g., at a constant linear velocity) by driving a spindle motor (not shown) to which the turntable is attached.

[0066] On one surface of this optical disk 11, there are provided an information recording area 29 a on which information can be recorded and which is opposed by an optical head of an optical pickup device incorporated within the disk recording and reproducing apparatus and a non-recording area 29 b on which information cannot be recorded. The non-recording area 29 b is comprised of an inner non-recording area 29 b having a predetermined width provided on the outside of the center hub 23 which is in the inside of the optical disk 11 and an outer non-recording area 29 b having a predetermined width provided on the outer peripheral edge of the optical disk 11. An information recording area 29 a is provided between the inner and outer non-recording areas 29 b and 29 b. As a material of a substrate of this optical disk 11, synthetic resins such as polycarbonate (PC) and polyolefin should be suitably used. It is needless to say that other synthetic resins can be used and that the above materials are not limited to the synthetic resins and that various materials such as a glass material and an aluminum alloy which can be used as an information recording medium may be used.

[0067] An opening window 30 is bored at substantially central portions of one side edge portions 13 b, 15 b of the upper and lower shells 13, 15 so as to expose part of the outer peripheral surface of the middle shell 14. This opening window 30 is comprised of an upper recess portion 30 a provided on the joint portion of the upper shell 13 and a lower recess portion 30 b provided on the joint portion of the lower shell 15. Further, on one side edge portions 13 b, 15 b of the upper and lower shells 13, 15, there is provided a guide groove 31 which is extended along the joint surface in the front and back direction. This guide groove 31 is provided in order to prevent a mis-insertion from being carried out when the disk cartridge 10 is loaded onto the disk recording and reproducing apparatus. The opening window 30 is communicated with the guide groove 31. 31 On the front corner portions of one side edge portions 13 b, 15 bof the upper and lower shells 13, 15, there is provided a lock storing portion 33 in which a lock member 32 can be stored rotatably. This lock storing portion 33 is communicated with the concave portions 19 a, 19 b and is communicated with the guide groove 31 through an opening hole 34 bored through one side edge portions 13 b, 15 b. Further, on the lock storing portion 33 of the upper shell 13, there is provided a support shaft 35 which rotatably supports the lock member 32 in such a manner that it may be protruded from the lower shell 15 side.

[0068] This lock member 32 is formed of a lever-like member which is rotatably fitted into a supporting shaft 35 in such a manner that it can be swung in the plane direction as shown in FIGS. 2, 14 and the like. A stopper portion 36 having a plurality of teeth is provided at the lock member 32 at its one end in the longitudinal direction. Further, the lock member 32 has a spring piece 38 integrally formed therewith and which is protruded in the same direction so as to oppose to the stopper portion 36.

[0069] The lock member 32 having the above arrangement is fitted into the supporting shaft 35 when the stopper portion 36 is faced toward the concave portions 19 a, 19 b side. The spring piece 38 is brought in contact with the inner surfaces of the front edge portions 13 a, 15 a. Under spring force of this spring piece 38, the stopper portion 36 is spring-biased toward the concave portions 19 a, 19 b side. Concurrently therewith, the input portion 37 is extended through the opening hole 34 from the inside and is protruded into the guide groove 31.

[0070] The middle shell 14 which is rotatably fitted into the upper and lower concave portions 19 a, 19 b of the upper shell 13 and the lower shell 15 has the arrangement shown in FIGS. 2, 6 and the like. This middle shell 14 includes a flat surface portion 40 formed of a disk-like thin plate material and a ring portion 41 continuously formed at the outer peripheral edge of the flat surface portion 40. The flat surface portion 40 of the middle shell 14 is comprised of a pair of semicircle pieces 40 a, 40 a formed as substantially semicircular shapes. An opening portion 42 is formed by forming a spacing between chord sides of the two semicircle pieces 40 a, 40 a. This opening portion 42 has a shape and a size equal to those of the opening portion 25 of the lower shell 15.

[0071] Specifically, similarly to the opening portion 25, the opening portion 42 includes a table opening portion 42 a set at the central portion of the flat surface portion 40 and into and from which the turntable is inserted and ejected and head opening portions 42 b, 42 bset on both sides in the diametrical direction of the table opening portion 42 a and to which optical heads are opposed. On the inner peripheral edge of the flat surface portion 40 a which surrounds the table opening portion 42 a, there is provided a supporting edge portion 40 b which supports from the lower direction the inner non-recording area 29 b of the optical disk 11 when it is in a state of being free.

[0072] On the outer peripheral surface of the ring portion 41 of the middle shell 14, there is provided a gear portion 43 having a large number of gear teeth over a predetermined range of the peripheral direction. As shown in FIG. 14, in assembling the cartridge housing, when the opening portion 42 of the middle shell 14 is made coincident with the opening portion 25 of the lower shell 15, this gear portion 43 is set at the position in which it is opposed to the opening window 30. The range of this gear portion 43 is set to be an angular range slightly larger than the rotation angle of the middle shell 14. Specifically, as shown in FIGS. 16 to 20, when the pair of shutter members 18 a, 18 b are completely closed such that the opening portion 42 is inclined by a maximum inclination angle relative to the opening portion 25, one end of the circumferential direction of the gear portion 43 is exposed to the opening window 30. Then, when the pair of shutter members 18 a, 18 b are completely opened such that the middle shell 14 is rotated by a predetermined angle to cause the opening portion 42 to overlap the opening portion 25, the other end of the circumferential direction of the gear portion 43 is exposed to the opening window 30.

[0073] On the outside of one end of the gear portion 43 of this middle shell 14, there is provided a stopper portion 44 for limiting the rotation movement amount of the middle shell 14 in such a manner that it may be protruded toward the outside of the radius direction. Since the gear portion 43 and the stopper portion 44 are projected from the outer peripheral surface of the ring portion 41 to the outside as described above, relief grooves 45 a, 45 b are respectively provided on the upper shell 13 and the lower shell 15 at their corresponding portions to avoid contacting with the stopper portion 44 and the like such that they can be allowed to pass. Further, on one end face of the ring portion 41, there are provided three circular-arc-like cam portions 46 (portions shown by a large number of dots in FIG. 6), each having a predetermined length, continued in the circumferential direction. These cam portions 46 are respectively engaged with the three cam grooves of the upper shell 13 while the middle shell 14 is assembled on the upper shell 13. When this middle shell 14 is rotated at a predetermined angle, the respective cam portions 46 are overlaid on the three lift up portions 23, respectively.

[0074] On the other end face of the ring portion 41 of the middle shell 14, there are provided two circular-arc-like protruded rail portions 47 which are protruded on the opposite side of the cam portions 46. These protruded rail portions 47, 47 are used to restrict the pair of shutter members 18 a, 18 b not to move to the outside of the radius direction. To avoid the contact with these protruded rail portions 47, 47, one cover portions 26 a, 26 a of the upper shell 13 have relief grooves 48 extended in the circumferential direction, respectively as shown in FIG. 7. Further, on the flat surface portion 40 of the middle shell 14, there are respectively provided a pair of supporting apertures 49, 49 which are used to support the pair of shutter members 18 a, 18 b such that the pair of shutter members become freely rotatable in the plane direction. The pair of supporting apertures 49, 49 are each set in one edge portions of the head opening portions 42 b, 42 b with the table opening portion 42 a as the center in a point-symmetrical fashion.

[0075] A shutter mechanism 18 that is attached to the middle shell 14 through the pair of supporting apertures 49, 49 is comprised of the pair of shutter members 18 a, 18 b which are the same in shape and size. The pair of shutter members 18 a, 18 b have the shape and structure shown in FIGS. 8 and 9. Specifically, the pair of shutter members 18 a, 18 b are each formed of substantially a semicircular thin plate material. At substantially a central portion of a chord side of each of the shutter members 18 a, 18 b, there are provided stepped portions 50 having a predetermined length in the direction perpendicular to the normal. This stepped portion 50 forms at its both sides a convex-side joint portion 50 a and a concave-side joint portion 50 b.

[0076] On the respective joint portions 50 a, 50 b of the shutter members 18 a, 18 b, there are respectively provided overhang portions 51, 51 which are overhung in the direction perpendicular to the direction in which the chords are extended. Thus, in the pair of shutter members 18 a, 18 b, the end face of the convex-side joint portion 50 aand the end face of the concave-side joint portion 50 b are respectively opposed to each other, whereby the overhang portion 51 aof the convex-side joint portion 50 a are overlaped to the overhang portion 51 b of the concave-side joint portion 50 b. Shaft portions 52 which are projected toward the overhang portions 51 side are respectively attached to shaft attachment portions 50 c which are end portions of the convex-side joint portion 50 a side of the chord sides of the shutter members 18 a, 18 b.

[0077] The shaft portions 51 are fitted into the supporting apertures 49 of the flat surface portion 40, whereby the respective shutter members 18 a, 18 b are rotatably attached to the middle shell 14. In this case, the pair of shutter members 18 a, 18 b are attached to the middle shell in such a manner that their chord sides are opposed to each other. As a result, as shown in FIG. 8, when the pair of shutter members 18 a, 18 b are rotated so as to become distant from each other on the outside, respectively, the respective shutter members 18 a, 18 b are mounted on the semicircular pieces 40 a such that they are hidden by the semicircular pieces. On the other hand, when the pair of shutter members 18 a, 18 b are inwardly rotated such that their joint portions 50 a, 50 b are brought in contact with each other, a substantially circular cover portion is formed at the central portion of the opening portion 42 by the pair of shutter members 18 a, 18 b as shown in FIG. 9.

[0078] Further, on the concave-side joint portions 50 b of the shutter members 18 a, 18 b, there are respectively provided open and close grooves 53 which are used to open and close the shutter members 18 a, 18 b. The open and close grooves 53 are extended in the radial direction from the shaft portions 52 of the shutter members 18 a, 18 b. The operational convexs 27 a, 27 b of the lower shell 15 are slidably engaged with the open and close grooves 52. Further, at the end portions on the outsides of the respective open and close grooves 53, there are provided resilient pieces 54 formed by cutting and concave portions 53 a which are used to relieve the operational convexs 27 a, 27 b. On the circular-arc-like sides of the shutter members 18 a, 18 b, there are provided close pieces 55 which are used to close openings left after the shaft portions 52 had been moved while the shutter is being closed.

[0079] The upper shell 13, the middle shell 14, the lower shell 15 and the shutter members 18 a, 18 b having the above arrangements may be made of synthetic resins such as ABS resin (acrylonitrile-butadiene-styrene resin) and HIPS (high impact polystyrene). However, it is needless to say that they may be made of other synthetic resins and metal materials such as an aluminum alloy and a stainless steel.

[0080] The above middle shell 14, the operational convexs 27 a, 27 b, a rack rod 70 and the like constitute a shutter opening and closing mechanism. Then, the supporting apertures and the shaft portions 52 constitute a rotary coupling portion, and the operational convexs 27 a, 27 b and the open and close grooves 53 constitute a movement coupling portion. Although not shown, the cartridge housing 12, for example, of the disk cartridge 10 has at its rear corner portion a write-protect mechanism for preventing information recorded on a recording medium such as an optical disk from being erased by mistake. Such write-protect mechanism can be comprised of an operation window opened on the back of the cartridge housing 12, a write-protect piece attached so as to open and close this operation window and the like.

[0081] The disk cartridge 10 having the above arrangement can be assembled with ease as follows, for example. As shown in FIG. 2, an assembly work of this disk cartridge 10 is executed in the state in which the upper shell 13 is disposed in the lower direction. First, the optical disk 11 is installed within the upper-side concave portion 19 a of the upper shell 13. At that very moment, the optical disk 11 is inserted into the upper-side concave portion 19 a while its surface with the center hub 28 is being faced to the lower direction. Next, the opening side of the middle shell 14 is fitted into the upper-side concave portion 19 a to cover the optical disk 11, whereby the optical disk 11 is rotatably stored within the disk compartment 16 comprised of the middle shell 14 and the upper shell 13. At that very moment, the direction in which the opening portion 42 of the middle shell 14 is extended is made coincident with the front and back direction of the upper shell 13 and one end of the gear portion 43 is faced to the opening window 30.

[0082] Next, the shutter mechanism 18 is assembled on the middle shell 14. In this assembly work, while the chord sides of the pair of shutter members 18 a, 18 b are being opposed to each other, the shaft portions 52 are respectively fitted into the supporting apertures 49 of the flat surface portion 30 in this state. Then, the respective shutter members 18 a, 18 b are separated from each other and are thereby overlapped on the semicircular pieces 40 a of the middle shell 14. Concurrently therewith or before or after the above assembly work, the lock member 32 is attached to the supporting shaft 35 of the lock storage portion 33. In that case, the spring piece 38 of the lock member 32 is brought in contact with the inner surface of the front edge portion 13 a of the upper shell 13, and the input portion 37 is projected from the opening hole 34 into the guide groove 31 under spring force of this spring piece 38.

[0083] Next, the lower shell 15 is laid over the middle shell 14 including the shutter mechanism 18, and the lower shell 15 is overlaped to the upper shell 13. At that time, the positioning convex portions 24 a, 24 b of the lower shell 15 are fitted into the positioning concave portions 21 a, 21 b of the upper shell 13, whereby the lower shell 15 is automatically and properly positioned relative to the upper shell 13. In that case, when the pair of shutter members 18 a, 18 b are disposed at the above positions, the pair of operational convexs 27 a, 27 b provided within the lower-side concave portion 19 b of the lower shell 15 can be respectively opposed to the pair of open and close grooves 53. Therefore, only by overlapping the lower shell 15 on the upper shell 13 without considering the positions of the pair of open and close grooves 53, the pair of operational convexs 27 a, 27 b can be engaged with the pair of open and close grooves 53.

[0084] Thereafter, the lower shell 15 is overlaped to and fixed to the upper shell 13 by using a plurality of fixing screws. Thus, the assembly work of the disk cartridge 10 is completed. In this case, without using a fixing means comprised of independent members such as fixing screws, the joint surfaces of the upper shell 13 and the lower shell 15 can directly be joined by using a suitable means such as an adhesive agent. As described above, according to the disk cartridge of this embodiment, the number of assemblies can be decreased and the assembly work can be carried out extremely easily.

[0085] In this case, the joint portions 50 a, 50 b of the pair of shutter members 18 a, 18 b have the overhang portions 51 a, 51 b, each having about half thickness and these overhang portions 51 a, 51 b are inserted beneath the other joint portions 50 a, 50 b, respectively. Therefore, since the overall arrangements of the joint portions 50 a, 50 b are properly overlapped with each other, a labyrinth effect can be achieved so that the disk cartridge can be prevented from being smudged by dusts and the like over the whole length of the joint portions 50 a, 50 b. In addition, when the joint portions 50 a, 50 b are pressed inwardly, external force applied to the joint portions 50 a, 50 b is received by the overhang portions 51 a, 51 b located at the inside. Consequently, the overhang portions 51 a, 51 b the engagement state between the joint portions 50 a and 50 b can be strengthened more by the overhang portions 51 a, 51 b, whereby the shutter members can be prevented from being deformed and the disk cartridge can be prevented more reliably from being smudged by dusts and the like.

[0086]FIG. 3 shows the state presented before the disk cartridge 10 having the above arrangement is loaded on the disk recording and reproducing apparatus. Specifically, the pair of shutter members 18 a, 18 b of the shutter mechanism 18 completely close the opening portion 25 of the lower shell 15 and the opening portion 42 of the middle shell 14 due to its own tare and frictional force generated between the lower shell 15 and the middle shell 14. Further, the three cam portions 46 of the middle shell 14 are projected from the three cam grooves 22 of the upper shell 13 and are thereby laid over the lift up portions 23. As a consequence, the pair of shutter members 18 a, 18 b are sandwiched from both sides by the upper shell 13 and the middle shell 14.

[0087] Further, as shown in FIG. 14 and the like, the stopper portion 36 is engaged with the gear portion 43 of the middle shell 14 under spring force of the spring piece 38 of the lock member 32. Consequently, the pair of shutter members 18 a, 18 b are doubly locked by a holding mechanism based on cam elevation operations and a lock mechanism based on the lock member 32. Accordingly, the state in which the opening portions 25, 42 are closed by the shutter mechanism 18 can be held with high reliability and the shutter mechanism 18 can reliably be prevented from being opened by mistake due to some cause such as vibrations.

[0088] When the disk cartridge 10 in this state is inserted into a disk recording and reproducing apparatus 60 as shown in FIGS. 26 and 27, the lock member 32 is released from the locked state by a shutter opening and closing mechanism provided in this disk recording and reproducing apparatus 60. Thereafter, this shutter opening and closing mechanism opens the shutter mechanism 18 to open the opening portions 25, 42. The manner in which this shutter mechanism 18 is opened and closed will be described in detail later on.

[0089] Next, the disk recording and reproducing apparatus 60 will be described. As shown in FIGS. 26 and 27, this disk recording and reproducing apparatus 60 comprises an outer case 61 formed of a hollow housing, a recording and reproducing apparatus body 62 stored within this outer case 61 and the like. The outer case 61 includes a case body 63 which is opened in the upper surface and the front, a case lid 64 detachably attached to the upper portion so as to close the upper surface of the case body 63, a front panel 65 detachably attached to the front portion so as to close the fronts of the case body 63 and the case lid 64 and the like.

[0090] The case body 63 is provided with four leg assemblies 63 a which are projected in the lower direction. The disk recording and reproducing apparatus 60 is supported by these leg assemblies 63 aand thereby attached to the proper position. The front panel 65 is formed of an oblong plate-like member, and an oblong cartridge slot 66 is formed on the upper portion of the front panel. The cartridge slot 66 has approximately the same dimension as that of the front side of the disk cartridge 10. This cartridge slot 66 is constantly closed by an open and close lid 67 disposed on the inside of the cartridge slot.

[0091] This open and close lid 67 is pressed by the front portion of the disk cartridge 10 and the disk cartridge is inserted into the cartridge slot at its predetermined position as shown in FIG. 27. As a result, the disk cartridge 10 is automatically loaded into the disk recording and reproducing apparatus by a loading mechanism not shown. Then, the disk cartridge 10 transported by the loading mechanism is properly located at a predetermined position and fixed thereto within the disk recording and reproducing apparatus 60. Concurrently therewith or before and after the above operation, the shutter opening and closing mechanism provided in the disk recording and reproducing apparatus 60 operates the shutter mechanism 18 to open the opening portions 25, 42.

[0092] Thereafter, a turntable 68 a of a disk rotary drive apparatus 68 and an optical head 69 a of an optical pickup device 69 are entered into the opening portions 25, 42 thus opened. Then, the turntable 68 a is engaged with the center aperture 11 a of the optical disk 11 and the center hub 28 is attracted and held by a magnet incorporated within the turntable 68 a. Concurrently therewith or before and after the above operation, the optical head 69 a is approached to a predetermined position of the information recording area 29 a of the optical disk 11, whereby the disk recording and reproducing apparatus 60 becomes able to record an information signal on the optical disk 11 and to reproduce a recorded information signal from the optical disk.

[0093] The recording and reproducing apparatus body 62 of the disk recording and reproducing apparatus 60 comprises constituents shown in FIG. 25, for example. Specifically, the recording and reproducing apparatus body 62 includes three control apparatus of a system controller S1, a memory controller S5 and a drive controller D1. The system controller S1 and the memory controller S5 are directly connected, and a read-only memory apparatus (ROM (read-only memory)) S2 and a read and write memory apparatus (RAM (random-access memory)) S3 are connected to a connection line between the system controller and the memory controller. Further, a memory S4 and MPEG 2 (moving picture compression system applied to existing television broadcasting capable of 3 M to 40 Mbps, HDTV (high definition television) and broadband ISDN (integrated services digital network)) encoder S6 and decoder S7 are connected to the memory controller S5. Further, a control panel S8 and a remote control receiving section S9 are connected to the system controller S1.

[0094] An ECC D4 is connected to the drive controller Dl, and a memory apparatus (ROM) D2, a memory apparatus (RAM) D3, a servo circuit D6 and an address decoder D7 are connected to a connection line between the drive controller D1 and the ECC D4. Further, the drive controller D1 is connected with a recording error judgment circuit D8 for judging whether or not an error occurred upon recording. This drive controller D1 is connected through a command interface to the system controller S1. The drive controller is connected through the ECC D4 and a data interface to the memory controller S5 and a modem (modulator and demodulator) circuit D5. Then, the modem circuit D5 is also connected to the optical head 69 a of the optical pickup device 69.

[0095] The servo circuit D6 is connected to a spindle motor 68 which is serving as a disk rotary drive apparatus, the optical pickup device 69 and the recording error judgment circuit D8. Further, the optical pickup device 69 is connected to an address decoder D7, and this address decoder D7 is also connected to the recording error judgment circuit D8.

[0096] When the disk cartridge 10 is inserted into the disk recording and reproducing apparatus 60 having the above arrangement from the cartridge slot 66, as shown in FIG. 14, a rack rod 70 which shows a practical example of the shutter opening and closing mechanism incorporated within the disk recording and reproducing apparatus 60 is entered into the guide groove 31 formed on one side portion of the disk cartridge 10, whereby the input portion 37 of the lock member 32 projected into the guide groove 31 is pushed into the lock storage portion 33 by pressing force of the rack rod 70 against spring force of the spring piece 38. Further, when the rack rod 70 is advanced relatively, the tip end of the gear portion 70 a is meshed with the gear portion 43 of the middle shell 14.

[0097] This gear portion 43 is meshed with the gear portion 70 a of the rack rod 70, whereby the middle shell 14 is rotated in response to the moved amount of the rack rod 70 as shown in FIGS. 14 to 20. FIGS. 14 and 15 show the state presented before the gear portion 70 aof the rack rod 70 is meshed with the gear portion 43 of the middle shell 14. In this state, the convex-side joint portion 50 a and the concave-side joint portion 50 b of the pair of shutter members 18 a, 18 b are pressedagainst with each other and are thereby closely contacted with each other. At that very time, since the opening portion 42 of the middle shell 14 is located at the inclined position relative to the opening portion 25 of the lower shell 15, although only the central portion in which the two opening portions 25, 42 are overlapped with each other is opened, that opening portion is closed by the pair of shutter members 18 a, 18 b. Accordingly, the disk compartment 16 can be prevented from being smudged by dusts and the like from the overlapping portion of the opening portions 25, 42.

[0098] The shaft attachment portions 50 c of the pair of shutter members 18 a, 18 b are interposed at the portions in which the opening portions 25 and 42 are close to each other with an acute angle, and the shaft attachment portion 50 c is located at the inside of one cover portion 26 b, thereby removing the space. The closing piece 55 is interposed at the inside of the other cover member 26 b, and this closing piece 55 is located at the inside of the other cover member 26 a, thereby removing the space. Further, the open and close grooves 53 provided on the pair of shutter members 18 a, 18 b are respectively closed by the lower shell 15. Therefore, since all spaces from the opening portion 25 of the lower shell 15 to the opening portion 42 of the middle shell 14 are completely closed by the pair of shutter members 18 a, 18 b, the disk compartment 16 can be prevented from being smudged by dusts and the like through the opening portions 25, 42.

[0099] In this state, when the rack rod 70 is being entered into the guide groove 31 as the disk cartridge 10 is being inserted into the disk recording and reproducing apparatus and the gear portion 70 and the gear portion 43 of the middle shell 14 commence to be meshed with each other, the middle shell 14 is rotated in the counter-clockwise direction in FIG. 14. In this case, in the initial state in which the middle shell 14 commences to rotate, as shown in FIGS. 21C and 22A, the cam portion 26 is laid over the lift up portion 23 and sandwiches the pair of shutter members 18 a, 18 b between it and the upper shell 13 so that relatively large force is required to rotate the middle shell 14. When the middle shell 14 is rotated against large frictional force generated from the cam portion 46 so that the cam portion 46 passes the lift up portion 23 and enters the cam groove 22 as shown in FIGS. 21B and 22B, frictional force of the cam portion 46 is lost. Consequently, the middle shell 14 will be able to rotate extremely lightly and smoothly.

[0100] At that time, while the respective shaft portions 52 of the pair of shutter members 18 a, 18 b are similarly rotated as the middle shell 14 is rotated, the operational convexs 27 a, 27 b of the lower shell 15 are slidably engaged with the open and close grooves 54 provided on the other end side. The pair of operational convexs 27 a, 27 b are provided on the lower shell 15 and the operational convexs 27 a, 27 b are never moved. On the other hand, the open and close grooves 53 are extended in the direction S connecting the shaft portion 52 and the operational convex 27 b (or 27 a) in such a manner that they can be relatively moved within the operational convexs 27 a, 27 b as the shutter members 18 a, 18 b are rotated.

[0101] As a result, the operational convex 27 b (or 27 a) is moved within the open and close groove 53 toward the shaft portion 52 side in response to the rotation amounts of the shutter members 18 a, 18 b. Thus, in each of the shutter members 18 a, 18 b, the shaft portion 52 is moved toward the corresponding operational convex 27 b (27 a) side. Consequently, the respective shutter members 18 a, 18 b are moved on the corresponding semicircular pieces 40 from the state shown in FIG. 16 through the states shown in FIGS. 17, 18 and 19 as shown in FIG. 20. Thus, the respective shutter members 18 a, 18 b are overlapped on the semicircular pieces 40 a so that the upper and lower opening portions 25, 42 are opened completely as shown in FIG. 10 and the like. Therefore, a part of the optical disk 11 stored within the disk compartment 16 is exposed through the opening portions 25, 42.

[0102] As a consequence, as shown in FIG. 13, the turntable 68 a and the optical head 69 a can be inserted into the opening portions 25, 42. Accordingly, the turntable 68 a or the like is moved toward the disk cartridge 10 side or the disk cartridge 10 is moved toward the turntable 68 a side, whereby the turntable 68 a is entered into the table opening portion 25 a provided at the central portion and the optical head 69 a is entered into the head opening portion 25 bprovided at both sides. As a result, the optical disk 11 is loaded on and chucked to the turntable 68 a and the optical head 69 a is opposed to the information recording area 29 a of the optical disk 11 with a predetermined space with the result that the disk recording and reproducing apparatus 60 becomes able to reproduce or record an information signal from or on the information recording area 29 a of the optical disk 11.

[0103] Accordingly, the recording and reproducing apparatus body 62 is operated, the optical disk 11 is rotated by driving the spindle motor 68 through the turntable 68 a, laser light is emitted from the optical head 69 a by driving the optical pickup device 69 and the information signal can be read out from the information recording area 29 a or a new information signal can be recorded on the information recording area 29 a. Thus, the recording and reproducing apparatus body 62 can reproduce or record the information signal.

[0104] After the information signal had been reproduced or recorded as described above, when a user operates a cartridge eject button (not shown) provided on the disk recording and reproducing apparatus 60, for example, the disk cartridge 10 is ejected from the disk recording and reproducing apparatus 60 through the operation of the loading mechanism. Specifically, when the disk cartridge 10 is moved toward the cartridge slot 66 side by the eject operation of the loading mechanism, the rack rod 70 is retreated relatively.

[0105] When the rack rod 70 is retreated, the middle shell 14 and the pair of shutter members 18 a, 18 b are operated in the manner opposite to the above manner in which the optical disk is inserted into the recording and reproducing apparatus. Specifically, in the state in which the pair of shutter members 18 a, 18 b are completely opened as shown in FIG. 20, the middle shell 14 and the pair of shutter members 18 a, 18 b are rotated in the clockwise direction and the middle shell and the pair of shutter members are changed to the state shown in FIG. 16 through the states shown in FIGS. 19, 18 and 17. In the states shown in FIGS. 20 to 16, the cam groove 46 of the middle shell 14 exists within the cam groove 22 so that the middle shell 14 can be rotated by small force F.

[0106] Next, when the middle shell 14 is changed from the state shown in FIG. 16 to the state shown in FIG. 14, since the cam groove 23 is brought in contact with the lift up portion 23 and then laid over the lift up portion 23 so that the above frictional force is applied to the rotation of the middle shell 14. Then, immediately before the closed state shown in FIG. 14, the operational convex 27 b (or 27 a) moves the open and close groove 53 to the outermost portion so that the open and close groove comes in contact with and presses the resilient piece 54. As a result, spring force X is generated in the resilient piece 54 by pressing force of the operational convex 27 b(or 27 a). Under spring force X of this resilient piece 54, urging contact force Y which is acting on the other shutter member 18 a (or 18 b) is generated in the central stepped portion 50.

[0107] Since this urging contact force Y is generated in both of the pair of shutter members 18 a, 18 b, the airtightness of the pair of shutter members 18 a, 18 b can be improved more by their urging contact force Y. Accordingly, the disk compartment 16 can be more effectively prevented from being smudged by dusts and the like by improving the dustproof property at the joint portion of the pair of shutter members 18 a, 18 b.

[0108] Thereafter, aft the gear portion 70 a of the rack rod 70 had been disengaged from the gear portion 43, the rack rod 70 is passed through the opening hole 34, whereby the input portion 37 of the lock member 32 is projected from the opening hole 34 into the guide groove 31. Concurrently therewith, the stopper portion 36 is moved to the inside and is thereby meshed with the gear portion 34. As a result, the middle shell 14 is locked by the lock member 32 and its rotation is thereby stopped. Then, as shown in FIGS. 11 and 12, the whole of the opening portions 25, 42 is completely closed by the pair of shutter members 18 a, 18 b.

[0109]FIGS. 23 and 24 show a disk cartridge according to a second embodiment of the present invention. A disk cartridge 80 shown in this embodiment is of one-head type disk cartridge for use with a disk recording and reproducing apparatus using one head. As will be clear from FIG. 23, this disk cartridge 80 differs from the disk cartridge 10 shown in FIG. 2 and the like only in a lower shell 85. Therefore, elements and parts identical to those of FIG. 2 are marked with the identical reference numerals and need not be described. Only an opening portion 86 of the lower shell 85 having different arrangement will be described.

[0110] The opening portion 86 of the lower shell 85 has the same shape and arrangement as those of the opening portion 25 of the above lower shell 15 from which only one head opening 25 b is removed. Other shapes and arrangements are the same. The one head disk cartridge 80 can easily be manufactured by using the one head lower shell 85 instead of the 2-head lower shell 15, and hence the present invention can easily cope with a one-head type disk recording and reproducing apparatus and a two-head type disk recording and reproducing apparatus. In addition, according to this embodiment, the manufacturing and assembling lines can be made common and the present invention can properly cope with users' needs.

[0111] While the present invention has been described so far, the present invention is not limited to the above embodiments. For example, while the optical disk has been used as the information recording medium as described above, the present invention is not limited thereto and can be applied to magnetic disks such as a magneto-optical disk and a floppy disk and other various kinds of disk-like recording mediums. Further, while the present invention has been applied to the disk recording and reproducing apparatus for both of recording and reproduction as the information recording and reproducing apparatus as described above, the present invention is not limited thereto and can, of course, be applied to a disk recording apparatus or a disk reproducing apparatus which is capable of either recording or reproducing a disk.

[0112] While the opening portions 42, 25 are provided on the middle shell 4 and the lower shell 15 of the cartridge housing 12 as described above, the present invention is not limited thereto and the opening portion may be provided on the upper shell, for example, so that the disk can be accessed simultaneously from upper and lower directions of the cartridge housing 12. Further, the disk compartment may be comprised of the middle shell and the lower shell, the disk-like recording medium may be stored within the disk compartment and the opening portion may be provided on the upper shell. As described above, the present invention may be variously modified without departing from the gist thereof.

[0113] As described above, according to the disk cartridge of the present invention, in the disk cartridge including the cartridge housing having the disk compartment, the disk-like recording medium and the pair of shutter members, since the opening portion is extended in the diametrical direction of the disk-like recording medium through the central portion of the cartridge housing, two recording and/or reproducing head portions can simultaneously be inserted into the opening portion so that two recording and/or reproducing operations can be executed at the same time. Furthermore, the two recording and/or reproducing head portions can approach the innermost periphery of the disk-like recording medium and therefore, the disk cartridge can approach the innermost periphery of the disk-like recording medium with a high efficiency.

[0114] Accordingly, for example, while new information is being recorded on the disk-like recording medium, information that was recorded immediately after new information has been recorded can be reproduced for confirmation. Alternatively, one data can be divided and divided data can simultaneously be recorded on different areas of the disk-like recording medium, thereby making it possible to increase a data rate. Furthermore, the disk cartridge according to the present invention can be applied to a system apparatus in which two optical heads are disposed on the plane relative to the disk-like recording medium, and therefore there can be provided a two-head type disk cartridge which can meet with such requirements.

[0115] According to the disk cartridge of the present invention, since the cartridge housing includes the middle shell in addition to the upper shell and the lower shell, the middle shell is rotatably supported by the upper shell and the lower shell and the opening portion is bored through the middle shell and the upper shell or the lower shell, there can be formed the opening portion into and from which two recording and/or reproducing head portions can be inserted and ejected simultaneously. There can be provided the disk cartridge in which the opening portion can be opened and closed by the pair of shutter members.

[0116] According to the disk cartridge of the present invention, since the pair of shutter members are comprised of the combination of two substantially semicircular same plate materials, the pair of shutter members are symmetrically disposed across the opening portion, the guide grooves are provided on one side portions of the respective shutter members, the pivots are provided on the other side portions and the pivots are supported to the middle shell so as to become freely rotatable, the opening portion of the wide range can be opened and closed while the areas of the shutter members can be reduced. Therefore, an efficiency with which the opening portion is opened and closed can be increased, and the whole of the disk cartridge can be made compact and thin.

[0117] According to the disk cartridge of the present invention, since the pair of guide grooves are provided on one of the pair of shutter members and the cartridge housing and the pair of operational convexs are provided on the other of the pair of guide grooves and the guide grooves are moved along the operational convexs based on the rotation of the middle shell, the pair of shutter members can be moved with a high reliability so that the opening portion can be opened and closed smoothly and reliably.

[0118] According to the disk cartridge of the present invention, in the disk cartridge comprising the cartridge housing having the disk compartment, the disk-like recording medium and the pair of shutter members, since the disk cartridge includes the shutter opening and closing mechanism for moving the pair of shutter members based on the rotation of the middle shell so that the end faces of the pair of shutter members are pressedagainst with each other, the pair of shutter members can be contacted with each other reliably and strongly by rotating the middle shell. Therefore, the disk compartment can be prevented from being smudged by very small dusts and the like by reducing the space between the pair of shutter members and the cartridge housing. Hence, the dustproof property of the cartridge housing can be improved. Moreover, the disk cartridge can be reduced in thickness and improved in space factor so that the whole of the disk cartridge can be made compact and thin.

[0119] According to the disk cartridge of the present invention, since the pair of operational convexs are moved along the pair of guide grooves based on the rotation of the middle shell, the pair of shutter members can be rotated smoothly and reliably.

[0120] Further, according to the disk cartridge of the present invention, since the shutter open and close mechanism presses the pair of shutter members, the two shutter members can be closely contacted with each other so that the dustproof property of the cartridge housing can be improved.

[0121] Furthermore, according to the disk cartridge of the present invention, since the pair of shutter members are comprised of a combination of two substantially semicircular same plate materials and the pair of shutter members are symmetrically disposed across the opening portion, the pair of shutter members can be operated with a high reliability. Therefore, the opening portion can be opened and closed smoothly and reliably, and the whole of the disk cartridge can be made compact and thin.

[0122] Having described preferred embodiments of the invention with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise embodiments and that various changes and modifications could be effected therein by one skilled in the art without departing from the spirit or scope of the invention as defined in the appended claims. 

What is claimed is:
 1. A disk cartridge comprising: a cartridge housing in which a disk compartment is formed by overlapping a pair of shells; a disk-like recording medium rotatably stored within said disk compartment; and a pair of shutter members rotatably attached to said cartridge housing and exposing part of said disk-like recording medium by opening and closing an opening portion provided on said cartridge housing when they are moved, wherein said opening portion is extended in the diametrical direction of said disk-like recording medium through the central portion of said lower shell or said upper shell.
 2. A disk cartridge according to claim 1, wherein said cartridge housing includes a middle shell rotatably supported by said upper shell and said lower shell and said opening portion is formed through said middle shell and said lower shell or said upper shell.
 3. A disk cartridge according to claim 1, wherein said pair of shutter members are comprised of a combination of a pair of substantially semicircular same plate materials, said pair of shutter members are symmetrically disposed on one surface of said middle shell across said opening portion, said guide groove is provided on one side portion of a chord side in each of said shutter members and a shaft portion provided on the other side portion of said chord side is rotatably supported to said middle shell.
 4. A disk cartridge according to claim 2, wherein a pair of guide grooves are provided on one of said pair of shutter members and said cartridge housing, a pair of operational convexs which are slidably engaged with said guide grooves are provided on the other of said pair of shutter members and said cartridge housing, said guide grooves are moved along said operational convexs based on the rotation of said middle shell, whereby said pair of shutter members are enabled to open and close said opening portion.
 5. A disk cartridge according to claim 2, further comprising a shutter opening and closing mechanism for tightly closing said opening portion provided on said cartridge housing and from which a part of said disk-like recording medium is exposed by moving said pair of shutter members based on the rotation of said middle shell such that end faces of said pair of shutter members are pressed against each other.
 6. A disk cartridge according to claim 5, wherein said shutter opening and closing mechanism includes a pair of guide grooves provided on one of said pair of shutter members and said cartridge housing and a pair of operational convexs provided on the other of said pair of shutter members and said cartridge housing and which are slidably engaged with said guide grooves and said pair of shutter members are enabled to open and close said open and close portion by moving said guide grooves along said operational convex based on the rotation of said middle shell.
 7. A disk cartridge according to claim 6, wherein said pair of guide grooves include resilient members for supplying spring force to said pair of operational convex portions such that said pair of shutter members are spring-biased in the flat surface direction when said pair of shutter members are closed.
 8. A disk cartridge according to claim 5, wherein said pair of shutter members are comprised of a combination of a pair of substantially semicircular same plate-like materials, said pair of shutter members are symmetrically disposed on one surface side of said middle shell across said opening portion, said guide grooves are provided on one side portions of chord sides of the respective shutter members and pivots provided on the other side portions of said chord sides are supported to said middle shell so as to become freely rotatable. 